Na-ion batteries are attractive as an alternative to Li-ion batteries because of their lower cost. Organic compounds have been considered as promising electrode materials due to their environmental friendliness and molecular diversity. Herein, aluminum-coordinated poly(tetrahydroxybenzoquinone) (P(THBQ-Al)), one of the coordination polymers, is introduced for the first time as a promising cathode for Na-ion batteries. P(THBQ-Al) is synthesized through a facile coordination reaction between benzoquinonedihydroxydiolate (C6O6H22-) and Al3+ as ligands and complex metal ions, respectively. Tetrahydroxybenzoquinone is environmentally sustainable, because it can be obtained from natural resources such as orange peels. Benzoquinonedihydroxydiolate also contributes to delivering high reversible capacity, because each benzoquinonedihydroxydiolate unit is capable of two electron reactions through the sodiation of its conjugated carbonyl groups. Electrochemically inactive Al3+ improves the structural stability of P(THBQ-Al) during cycling because of a lack of a change in its oxidation state. Moreover, P(THBQ-Al) is thermally stable and insoluble in nonaqueous electrolytes. These result in excellent electrochemical performance including a high reversible capacity of 113 mA h g-1 and stable cycle performance with negligible capacity fading over 100 cycles. Moreover, the reaction mechanism of P(THBQ-Al) is clarified through ex situ XPS and IR analyses, in which the reversible sodiation of C=O into C-O-Na is observed.
Bibliographical noteFunding Information:
This research was supported by the National Research Foundation of Korea (NRF) Grant (No. NRF-2016R1A2B3015956 and NRF-2016R1D1A1A02937104) and the Materials and Components Technology Development Program of MOTIE/KEIT, Republic of Korea [10050477, Development of separator with low thermal shrinkage and electrolyte with high ionic conductivity for Na-ion batteries].
- coordination polymer
- organic compound
- sodium ion battery